Lessons Learned from a Revolving Door

I've been in Chicago for ten years now, so I have started to take revolving doors for granted. When I first arrived, though, I was mystified by how many downtown buildings were outfitted with these extremely inconvenient portals. There was a whole science that I hadn't yet learned about exactly how and when to attempt entry: should I zip in when the door was halfway open, but still in motion, or wait until the next quadrant opened up completely? Why are they so hard to push? How do you manage to keep upright when you and a rolling computer case are sharing the same rotating pie-wedge? (Pity the poor mother attempting to maneuver a folded-up stroller and a toddler through a revolving door!)
I have had to learn from experience that a big guy in the space ahead of me will push the door so fast that I have to speed up or be crushed by the onrushing panel behind me. I have had to learn not to push the door too hard when there is a little old lady in front of (or behind) me. I have had to learn that exquisite sense of timing that allows someone on the other side to enter at the same time as I, so that the door will continue to revolve evenly.
Revolving doors teach you to look around (no pun intended): to notice the other people who are sharing, or are about to share, this spinning space. Not a bad image for life on a spinning planet full of other people, is it?